Explained: How is world’s largest iceberg drifting away from Antarctica?

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The world’s largest The iceberg is floating.For the first time in more than 30 years, according to the British Antarctic Survey. Recent satellite images show that the Antarctic ice sheet A23a is being pushed past the northern tip of the Antarctic Peninsula by strong winds and waves.

The world’s largest glacier, called A23a, in Antarctica. (Reuters)

Oliver Marsh, a glaciologist at the British Antarctic Survey, said it was rare to see a glacier move this large and scientists were monitoring the course closely.

said Andrew Fleming, a remote sensing expert from the British Antarctic Survey. BBC The glacier has been melting for a year and now it seems to have picked up speed. “I asked a couple of colleagues about this, wondering if there might be a change in shelf water temperature that could trigger it, but it’s time for consensus.”

Here’s what you need to know about A23a and why and how it works

What is the A23a glacier and what happened?

The A23a iceberg is 400 meters thick and covers about 4,000 square kilometers, which makes it three times the size of New York City and twice the size of Greater London. It weighs about one trillion metric tons.

In the year Since the separation of West Antarctica’s Flechner-Rhone Ice Shelf in 1986, A23a has been closed after its base has been stuck to the bottom of the Weddell Sea.

Glaciers can go to the southern ocean. It has been active since 2020. “It’s been on the ground since 1986, but eventually it will shrink enough to lose its grip and move,” Fleming said. I see the first movement in 2020.

British Antarctic Survey glaciologist Oliver Marsh said. Reuters“Over time it probably got a little more buoyant, allowing it to lift off the ocean floor and be pushed by ocean currents.”

A23a once had a Soviet research station. Moscow sent an expedition to retrieve equipment from the Druzhnaya 1 base, as it could be destroyed. However, the shelf ice remained relatively close to the coast, and its deep keel kept it securely anchored to the mud bottom of the Weddell Sea, preventing its movement.

Since the 1980s, A23a has held the title of “largest current glacier”, often surpassed by larger but shorter-lived glaciers.

What next?

As most glaciers accelerate, A23a may be initiated into the Antarctic Circumpolar Current. Then it goes to the southern ocean, through the so-called “Ice Lake”, where many other glaciers can be seen floating in the dark water.

As it moves, A23a could once again threaten land loss on South Georgia Island, posing challenges for the region’s wildlife. The island serves as a breeding ground and feeding ground for millions of seals, penguins and seabirds. A huge glacier could block their access.

In the year In 2020, a similar threat occurred with glacier A68, along South Georgia, threatening to harm marine life and disrupt the food chain. Fortunately, A68 eventually split into smaller pieces, which also offer a solution for A23a.

Marsh said. Reuters“Ice of this scale has the potential to remain in the Southern Ocean for long periods of time, even if it is very warm, and could disrupt shipping as far north as South Africa.”

As reported CNNAs it is carried by ocean currents, the A23a can move eastward and currently travels five kilometers per day.

British Antarctic Survey scientists Ella Gilbert and Marsh said climate change is causing significant changes in Antarctic ice as A23a is disrupted by the ice shelf’s natural growth cycle, with the continent losing large amounts of ice each year.

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